The man, Gary Giordano, 50, is being held by police in Aruba while they investigate whether he was involved in her disappearance.

Authorities will use eyewitness testimony, surveillance video and new photos of Gardner to re-enact what might have happened. The photos of Gardner show her partying with Giordano in Aruba two nights before she disappeared. In one of the photos, she's with Giordano, and in the other, she's standing by herself.

In the photos, obtained exclusively by ABC News, Gardner is wearing the same ankle-length dress she wore the day she vanished from an isolated jetty.

Gardner, 35, has been missing since Aug. 2. Giordano has told authorities that the two went snorkeling and that the Maryland woman was swept out to sea by a strong current. The two were in the midst of a weeklong trip to the Caribbean.

Giordano of Gaithersburg, Md., has denied any wrongdoing in connection with Gardner's disappearance.

The re-enactment will happen between 4 and 6 p.m. – around the time of day that Gardner apparently vanished.

"The whole key of re-enactments is to try to go back and first of all understand and be clear about the movements of people prior to a criminal act occurring," retired FBI profiler and ABC News analyst Brad Garrett said. "Now, unfortunately, in this case you don't have a crime scene to eventually end your re-enactment."

Investigators have so far found no direct evidence linking Giordano to a specific crime. "Good Morning America" has learned that at least two eyewitnesses are expected to participate, but Giordano will not.

Giordano has refused to cooperate, according to multiple sources on the island.

Garrett said the re-enactment might also give authorities "a better view of inconsistencies" in Giordano's account.

Giordano and Gardner arrived at the Rum Reef Bar & Grill at Baby Beach around 3 p.m Aug. 2. They stayed for an hour, then left for the beach.

Shortly after 6 p.m. that same day, Giordano reappeared on security cameras. He was shirtless but was still wearing his toupee.

Witnesses have previously described him as eerily calm in the initial hours after Gardner vanished and said that his clothes weren't dripping with water like he'd been frantically searching for someone. They also told investigators that they saw blood on the beach and said Giordano had a cut on his throat. By the time Giordano reached the restaurant, it was closed.

Giordano told investigators he was trying to get help, rouse someone from the restaurant. The surveillance video shows him crisscrossing the restaurant from the bar to the patio and going around back. He appears calm.

Investigators said that it appeared that Giordano wanted to be visible on every camera at the restaurant as if to establish an alibi.

Since Gardner vanished, Giordano has inquired about a $1.5 million insurance policy on her. On July 30, the day before the trip, he submitted an insurance policy on Gardner by mail and fax. An insurance agent told the FBI said that no one she has dealt with in the entire year has both mailed a hard copy of their policy and faxed it in, noting Giordano's urgency in getting the documents in before the trip.

The insurance policy on Gardner is dated July 27, and is initialed and signed by Gardner, although the beneficiary information is filled out in Giordano's handwriting. Giordano listed his mother as his beneficiary on the forms.